Blow dryers have been around for decades. For heating, the traditional blow dryer uses a heating element made of a resistive wire (usually nichrome) wrapped around an insulative core for shape (usually a mica sheet). One example is shown in FIG. 1. As the dryer operates at various levels of power (e.g., high, medium, or low), varying amounts of current run through the resistive wire and the desired levels of heat output are achieved. This heating element construction is inexpensive, heats up quickly, and the power consumption can be fine-tuned by adjusting the length or thickness of the wire. For these reasons, they have become popular in the overwhelming majority of hair dryers today.
The blow dryer also wastes a lot of heat because the heating element is poorly insulated. FIG. 2 shows a thermal image of the casing of a typical commercial hair dryer in use under a thermal camera. While the majority of the power consumed by the dryer is due to the heating element, the figure shows that a significant portion of that power is warming the casing of the dryer.
The blow dryer typically receives power transmitted through a cord that is plugged into a wall outlet, limiting where the dryer can be used. One of the most significant technical barriers to implementing a battery-operated hair dryer is in supplying an adequate amount of power. Commercial hair dryers tend to fall in the 1600 W to 2000 W range, which presents challenges to power from a battery. A breakdown of the components providing this power, shows that 10 to 20% of the power consumed is through the motor with the remaining amount drawn by the heating element. As a result, modifications to the heating element present a significant opportunity to reduce the power consumption to the point where the device can be powered by a battery.
It would be desirable to develop a battery-operated blow dryer with a heating element design for low power consumption.